Page:Popular Science Monthly Volume 69.djvu/231

Rh point reached, an entirely new field has been opened before our eyes. The new autographs of earthquakes have characters dependent upon the distances the waves have traveled to produce the record; so that the observer at a station can unaided give the distance of the disturbance within 50 miles, an error negligible in view of the extended area disturbed.

By combining records made at several widely-separated stations, not only the distance from a given station, but a sufficiently exact location for each quake, is easily obtained. To have developed a great system of some forty such stations, scattered throughout the length and breadth of the globe, is the great service rendered to science by the British Association for the Advancement of Science, especially, and by the leader of its Seismological Committee, Professor John Milne. Thus it has been revealed that the great earthquakes of the planet are twenty-fold more numerous than those reported by observation in situ, and that most of them occur upon the floor of the ocean, where other methods of observation would have failed to reveal their presence.

The analysis of the complex of waves registered in the seismogram is extending our knowledge of the nature of the earth's interior, and affording the solution of problems which, in importance and in difficulty of approach from other directions, can only be compared with those now being solved by the study of radioactivity.

No attempt to sum up the achievements of seismological research during the past ten years should fail to note the fact that the Japanese have for systematic and thorough study of the general problems, but even more for the practical applications of these investigations to the amelioration of the conditions in an earthquake-tormented country, taken the first place among the nations. Italy, also, with almost a score of stations of the first rank and with two hundred correspondents scattered throughout its small territory (to telegraph the first news of a quaking to the main office at Rome), has played no mean part in the advance of the science.

The center of earthquake investigation upon the continent is now, however, the Imperial German Chief Station for Earthquake Investigation at Strasburg. Professor Gerland, its director, now issues the annual catalogue of earthquakes, and he has the credit of having organized, in 1903, the International Seismological Association, and of having founded its journal, the Beiträge zur Geophysik. The work of the station now devolves largely upon his highly-trained assistants, Professor Rudolph and Dr. Sieberg.

The writer assumes that a beneficent result may be expected to follow from the frightful calamity at San Francisco in the stimulation of seismological research in America; so that we may later take our proper share of both the labor and its rewards. The start can